1. Field of the Invention
The present invention relates to a coloring mechanism in which hidden letters (including numbers), figures, symbols, images etc. or characters (hereinafter referred to as "letters etc.") appear by rubbing surfaces with metal such as coins etc., and to a recording material provided with this mechanism.
2. Prior Art
In place of forgeable magnetic cards, scratch cards on which hidden letters etc. appear by rubbing their surfaces with coins etc. are widely used as prepaid cards for international telephone, internet, portable telephone etc. and as cards in a lottery for the convenience of revealing hit or miss at once.
Such scratch cards have letters etc. printed with UV hardening ink, dye ink, pigment ink etc. on a part or the whole of their surfaces where the letters etc. are hidden with silver- or gold-colored highly opaque masking materials, and the letters etc. hidden therein appear by removing the silver- or gold-colored masking materials by rubbing their surfaces with coins etc.
However, conventional scratch cards have the problem that if the masking materials with an e.g. silver or gold color are rubbed with coins etc., the resulting powder from the masking materials is generated to make hands, clothes dirty.
Another problem is that during transportation, the surfaces of scratch cards may be hit by a hard material by accident to cause removal of the silver- or gold-colored masking materials so that letters etc. hidden therein may appear.
A further problem is that if conventional scratch cards are rubbed with hard materials such as coins, printed letters etc. may be removed together with masking materials, so some cards require transparent varnish applied onto the face of printed letters etc., thus making the process cumbersome and increasing the production cost.
In view of the problems of the conventional scratch cards, the object of the present invention is to provide a new mechanism in which from a completely different viewpoint, letters etc. are made readable by rubbing with metal such as coins, as well as a recording material with the mechanism, for example a recording material with the new mechanism which can be preferably used not only in scratch cards but also in various cards, papers used in notebooks, copies, printers etc., decorative sheets, stickers, calendars, various slip papers, papers for manuals, and contracts for the purpose of hiding letters , as well as in various OA instruments, home electronic appliances, office instruments, and office supplies in order to provide them with production numbers, production dates, or serial numbers etc. for computer program in hidden forms.